Sanding control valve



Dec. 7, 1943. w. A. BALDWIN 2,336,156

. SANDING' l('ONI'RCH.: VALVE Filed July '7, 1942 `los '5 REVERSE RELAY FORWARD RE LAY Slwcntor Patented Dec. 7, 1943 SANDING CONTROL VALVE WayneA. Baldwin, Watertown, N. Y., assigner to TheNew York Air Brake Company, a corporation of New Jersey Application July 7.1942, Serial No. 450,059 I y 4 claims.

This invention relates tof sanding control valves, and particularly to a valve having two' sanding push buttons, either of which may be pushed to establish continuous forward or reverse sanding according to the button pressed, and a third push button which may be pushed to teiminate sanding initiated by either of the two sanding buttons.

The device is of general utility but was developed particularly to meet the requirements of steam locomotive service. In its preferred form, the sanding valve controls two sanding relay valves, one for forward and the other for reverse sanding, the two relays being differentiated in that one is inactive when its control pipe is vented and operates when the control pipe is charged, whereas the other is inactive when its control pipe is charged and becomes active upon venting of the control pipe. The use of two relays so differentiated is standard practice with applicants assignee.

In the accompanying drawing, the single gure is a section of the control valve,vwith the connections to main reservoir, the two relays and the sand traps diagrammed in miniature. Running (non-sanding) positions are shown. I

The sectional view of the sanding control valve is diagrammatic to the extent that all the valves are shown on the plane of section. This permits all ows to be traced in a single View, but in actual practice more compact arrangements are possible.

Air for sanding and for operating the controls is supplied through pipe I from any suitable source such as the main reservoir (not shown). Branches of line I lead to the body 2 of the sanding control valve,v and to the relays 3 and |03. The relay 3 is the forward relay and controls cleanout and sanding connections 4 `and 5 to forward sandtraps 6, one for each rail. The relay |03 is thereverse or backing relay and controls sandtraps |06 through connections |04 and |05.

The forward relay 3 has a control pipe .'I and is equipped with a device 8 which so reverses the characteristic operation of the relay 3 that when control pipe 1 is vented, sanding is stopped, and when control pipe l is put under pressure the relay causes sanding. The reverse relay has a control pipe |01 but no device analogous to 8, so that the relay |03 has the normal characteristics which are the reverse of those of relay 3. It suspends action when the pipe |01 is under pressure and starts its sanding cycle when the pipe |01 is vented.

The parts 3 and |03 here merely typify relays Which respond oppositely to pressure changes in their control pipes. Since relays so diversified were in use prior to the present invention, and since the details of their construction are here immaterial, the relays will not be describedfur-A ther.

The control of forward'sanding is exercised by controlling pressure in chamber I I in body 2. In this chamber is a double beat valve comprising a supply valve I2 coacting with supply seat I3 and exhaust valve I4 coacting with exhaust seat I5. Supply seat I3 communicates with a `branch of port 9 to which'vmain reservoir line I leads, and exhaust seat I5 leads to exhaust port I6.

The valves I2 and I4 are nested as shown, and a spring I'I urges both in a direction to close exhaust and open supply. A stem I8 in valve I4 offers a connection through which the valves may be shifted to open exhaust and close supply. Stem I8 is connected with a hub unit I9 clamped to the center of a diierential diaphragm unit comprising a smaller diaphragm 2| clamped at its periphery between body 2 and spacer ring 22 and a larger diaphragm 23 clamped at its periphery between spacer ring 22 and cap 24. A spring' 25 reacts between the hub I9 and cap 24 and acts oppositely to spring I'I.

A branch of main reservoir passage 9 leads to space 26 between the diaphragms while space 2'I at the inner side of diaphragm 2| is vented to atmosphere around stem I8 to exhaust port I6. Thus main reservoir pressure acting between the diaphragms biases them outward, overpowering spring 25 and permittingspring I'I to close exhaust valve I4 and open supply valve I2. Thus chamber I I is normally under pressure.

To vent chamber I I, main reservoir pressure is established in chamber 28 within cap 24. This equalizes pressures on the larger diaphragm 23 so that main reservoir pressure urges diaphragm. 2| inward, and assisted by spring 25 shiftsvalves. I2 and I4 to open exhaust and close supply so that pressure in chamber I falls to atmospheric.. To put chamber 28 under pressure, push but-- ton 29 is depressed and unseats the poppet valveA 3|. This admits main reservoir air from chamber 32, which is connected with a branch of pas-- sage 9 to chamber 33, passage 34 and chamber 28., The reverse sanding control includes parts. functionally identical with parts numbered to 34 and such parts are identified by the numerals II to |34.

As will be explained further, charging of chamt ber 28 causes the forward relay to sand continutively to control communications with extension of ports 34 and |34. Side ports 38 and |38 in the bushing lead via passage 39 to chamber 4|, Depression of push button 42 unseats check valve 43 and vents chamber 4| to atmosphere,

Depression of button 29 charges chamber 28 and hence Vents chamber Similarly depression of button |29 charges chamber |28. and-so. vents chamber Either chamber when vented may be recharged by depressing reset button 42.

Chamber is connected directly with control pipe |01, since venting of pipe |01 causes relay |03 to sand.

A different connection is used for the forward relay. Chamber is connected with chamber 4.4

beneath diaphragm 45, which is clamped bycap 46 over a chamber 41 in body 2. A branch .of main reservoir passage 9. leads. to chamber 41. A hub 48 at the center of the diaphragm carries a valve disc 49 and a spring 5| biases the hub 48. upward to cause disc 49 to seal on seat 52.. This.

' seat 52 controls. a passage 53 leading to vcontrolpipe. 1 and to whistle 54 (used to warn the Vengineer that sanding is 'in effect).

When chamber is charged to mai-n reservoir pressure, as normally it. is, pressures above and below diaphragm 45 are equal .and spring 5|. closes disc 49 against seat 52. When button 29. is. depressed to charge chamber 28V and vent .chamber Il, the diaphragm 4 5. moves down admitting main reservoir air to control line 1 `and blowing warning whistle 54 continuously. This causes forward relay 3A to operate.

lf part 8 be omitted, so that relay .3 hasv the same operating characteristic asyrelay |83., the

. parts 4.4 to 54 .may be omitted in which case Acon- The use of relays of diverse types is. illustrated in the allowed application of` Charles A. `Campbell, Serial No. 344,148, led July 5, 1940., since issued as Patent No.. 2,291,874, dated August. 4, 19.42. The sand traps indicated in .the present vapplication. are the .type illustrated in the -Camp bell Patent No.V 2,243,243, issued` May 427., .1941.

I claim.:

1. In a sanding control valve, the combination of a source of pressure iiuid; two pressure motor operated valves one controlling forward and the other reverse sanding; independently operable push-button Valves serving when actuated to activate selected ones of said pressure motor operated valves to cause sanding; a push-button operated reset valve; and a` pressure-responsive switch valve for connecting said reset valve in c0- active relation with the motor of an active pressure motor actuated valve. 2. In a sanding control Valve, the combination other. Vreverse Y sanding; independently operable motors of corresponding pressure operated valves to pressure derived from said source; a push-button vent valve; and 4a double seated check valve for connecting the last-named valve selectively with the motors .of said pressure motor operated valves.v

3. In a. sanding control system, the combination of .a source of pressure -uid; two admission and, exhaust valves; means biasing said valvesv to admission position; pressure motors each effective when under pressure to shift its valve to exhaust position; selectively operable valves for subiecting said pressure motors to pressure derived. from said source; a reset valve operable to vent pressure.; a pressure responsive switch valve Vent pressure.;` a pressureV responsive switch valve Subject to pressures in said motorsl and serv-ing to connect .a motor under pressure 'to the reset valve; .a pressure .controlled pneumatic sandingA relay valve .of the type which becomes active on.v

depletion .of pressure, .connected to be controlled directly4 by .one of-said admission and exhaust valves; a v.pressure .controlled Ypneumatic relayy valve of the type which becomes active upon de-v VelODment .of pressure; a pressure responsive valve-controlled by the .other admission and exhaust.. valve. and servi-ng in response .to lowered` pressure .to admit actuating pressure iiuid from saisi. source. to the second relay; and a combined whistle :andivent .serving to Ybleed 4actuating iluiolfrom'the second relay at a. rate less lthan the capacity .of the pressure responsive valve. 

